This is a good and relevant question. Our article is very specific to QTc prolongation,1 and we did not dive into the world of Parkinson disease or dementia with Lewy bodies specifically.
When a patient is a threat to self or others, quetiapine is preferred, as Figure 1 shows. However, if the patient can’t take oral medications, fast-acting injectable or sublingual formulations with a shorter half-life are the only option. Yes, olanzapine has some risk for extrapyramidal side effects despite being atypical, but it has less risk than haloperidol. Injection benzodiazepines, although often useful, are worrisome in geriatric patients because of their effects on respiration and the central nervous system. It is fair to say that quetiapine and olanzapine in this population are not equals, and olanzapine should be avoided if possible in patients with Parkinson disease or dementia with Lewy bodies.
- Copyright © 2026 The Cleveland Clinic Foundation. All Rights Reserved.
